Discussion paper: asbestos fiber exposures in a hard rock gold mine.
Dement-JM; Zumwalde-RD; Wallingford-KM
Ann NY Acad Sci 1976 May; 271(1):345-352
Fiber exposures in a hard rock gold (7440575) mine were investigated. Two hundred air samples were taken in the gold mine where significantly increased risks of malignant and non malignant respiratory disease had been reported among a cohort of miners. Fiber concentrations recovered were determined by phase contrast optical microscope counting techniques. Fibers were examined using transmission/scanning electron microscopy with energy dispersive X- ray spectrometry. The mean airborne fiber concentration in samples from this mine was 4.82 fibers/cubic centimeter (cm3) in a range from 0.66 to 11.79 fibers/cm3. The range of fibers greater than 5 micrometers was from 0.07 to 1.29 fibers/cm3, with a mean of 0.36 fiber/cm3. Eighty to 90 percent of the fibers were identified by electron diffraction as amphibole. Approximately 20 percent of the airborne fibers were either too thick or too thin to give identifiable diffraction patterns and were, therefore, not classified. However, many of these fibers had chemical compositions identical to that of amosite asbestos. Sixty to 70 percent of identified amphibole fibers were grunerite (14640789), 10 to 15 percent were hornblende, and 1 to 2 percent were cummingtonite (12419475). Scanning electron microscopy also demonstrated the fibrous nature of the amphibole particles. The authors conclude that fibrous grunerite (amosite) is present in low concentrations in this hard rock gold mine, with most fibers shorter than 5microm in length. This suggests that the OSHA 1976 asbestos standard of 2.0 fibers greater than 5microm in length/cm3 may not be adequate to protect against asbestos induced respiratory neoplasia. A routine sampling method that more adequately accounts for short fibers must be developed and more attention should be paid to the adverse health implications of these short asbestos fibers.
NIOSH-Author; Microscopic-analysis; Mining-industry; Dust-exposure; Exposure-levels; Monitoring-systems; Asbestos-dust; Metal-dusts; Pulmonary-system-disorders; Spectrographic-analysis; Analytical-methods; Air-monitoring
7440-57-5; 14640-78-9; 12419-47-5
Annals of the New York Academy of Sciences